#include <iostream>
using namespace std;

double Area(double a); 
double Area(double a, double b); // 重载函数

int main()
{
    cout  << Area(3, 4) << endl;
    cout  << Area(3) << endl;

    return 0;
}

double Area(double a)
{
    return a;
}

// 重载
double Area(double a, double b)
{
    return a * b;
}